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	cell phones in TutorGig Encyclopedia (Site not responding. Last check: 2007-10-21)
		A reversible cell is a type of electrochemical cell also called a Galvanic cell and a voltaic cell in which reversing the current reverses the cell reaction.
		A K cell or a killer cell is a lymphocyte with immunoglobulin Fc receptors, which allow it to bind to and kill antibody coated cells by antibody dependent cell mediated cytotoxicity ADCC.
		Cell fractionation is the separation of homogeneous sets from a heterogeneous population of cells.
	www.tutorgig.com /es/cell+phones (997 words)

	Medmicro Chapter 5 (Site not responding. Last check: 2007-10-21)
		For each Hfr strain the point of arrowhead is the origin for chromosomal transfer; oriented transfer of chromosome during conjugation proceeds from point of arrowhead, followed immediately by base of the arrowhead, and so on.
		In matings between Hfr and F- strains, the segment of the F plasmid containing the tra region is transferred last, after the entire bacterial chromosome has been transferred.
		Prokaryotic cells (including bacteria) or eukaryotic cells (including yeast, animal or plant cells) can be used as recipients, but they differ with respect to their permissiveness for specific replicons, the transcriptional signals that they recognize, and the post-translational modifications of protein structure that they can accomplish.
	www.bact.wisc.edu /Bact303/Genetics/MedMicroChapter5 (14969 words)

	BIOLOGY 2140 “UNIT TWO” LECTURE OUTLINE
		NK cells have the same targets as cytotoxic T cells but they are not antigen specific and operate by mechanisms which are not well defined.
		The helper T cell, activated by the antigen, by a non-antigen protein co-stimulus, and by IL-1 and TNF secreted by the APC, secretes IL-2, which then causes the helper T cell to proliferate into a clone of cells that secrete additional cytokines.
		NK cells and macrophages are also stimulated by helper T cell cytokines, particularly IL-2 and interferon-gamma, to attack and kill virus-infected or cancer cells.
	coursedocs.slcc.edu /biol/jrudolph/2140T4T6T7out.htm (2891 words)

	Bacterial Interrupted mating Experiment
		The genes that are passed to the recipient cell become incorporated into the main bacterial chromosome by two crossover events.
		Once the transfer was stopped the cells were removed from the mating mixture and then were plated on a selective medium, specially conceived to allow only the growth and division of the recombinant cells.
		The later the gene enters the recipient cell, the smaller is the maximum frequency of recombinants because the probability of the mating cells breaking apart as the result of the Brownian motions increases with time.
	charon.chez.tiscali.fr /micro5.htm (1106 words)

	GeneTrans_LecOut
		conjugation- cell to cell contact mediated by the sex-pilus is required for DNA transfer.
		F-plasmid- donor cell, designated the male cell, synthesizes a sex-pilus which is encoded by genes on the F (fertility) plasmid.
		cell, but recipient cell may know have two copies for certain genes (one copy on plasmid and another on chromosome of recipient).
	faculty.washington.edu /jclara/301/M301lecOut/GeneTrans.html (931 words)

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	Bacterial Recombination (Site not responding. Last check: 2007-10-21)
		F' cells are able to initiate conjugation with F- cells because of the presence of the F factor.
		The cell that was F- now has the F factor (along with the piece of chromosomal DNA) and is therefore now F'.
		This cell, however, also has a complete chromosome, so it will be diploid for the segment of chromosomal DNA on the episome.
	www.emunix.emich.edu /~rwinning/genetics/bactrec4.htm (277 words)

	Lecture 7: microbial recombination and genetic engineering (Site not responding. Last check: 2007-10-21)
		cells also have the ability to produce pili which allow them to attach to other cells and transfer a copy of their F factors into these cells.
		These cells lack the fertility factor, lack the pili, but are capable of being attached to and receiving DNA from a "fertile" cell.
		These cells also transfer DNA into F- cells, but they start with the DNA farthest from the F factor (which is of course, next to the F factor, because the genome is circular) and keep transferring down the chromosome.
	nas.cl.uh.edu /novotny/genh7.htm (1093 words)

	Bacterial Recombination
		The Hfr cell is still able to initiate conjugation with an F- cell.
		This cell will receive new DNA from the Hfr cell however, and this new DNA can undergo recombination at a high frequency with the host chromosome, because the DNA sequences will be homologous.
		If this cell undergoes conjugation with an Hfr cell that is a+, b+ (in other words, wild type), the F- cell should undergo gene conversion to a+, b+ when both of those genes have been transferred by conjugation.
	www.emunix.emich.edu /~rwinning/genetics/bactrec3.htm (486 words)

	AC impedance measurement, internal cell resistance measurement and DC voltage monitoring (Site not responding. Last check: 2007-10-21)
		In addition to measuring DC cell voltage, they are capable of a highly accurate AC impedance measurement technique for the determination of complex electrical impedance.
		Using this information the user accurately pinpoints the internal resistance of a fuel cell, and subsequently its overall electrical efficiency.
		This provides the means to effectively characterize the internal components of fuel cells, including membrane specific data, allowing the developer to optimize their fuel cell’s operating parameters for rigorous practical applications
	www.hydrogenics.com /greenlight/products_diagnostics_hfr.asp (172 words)

	Lecture 2 (Site not responding. Last check: 2007-10-21)
		When an Hfr cell meets an F? cell, conjugation is initiated and the F plasmid takes with it the chromosomal DNA sequences to which it is now linked.
		The DNA that is passed from Hfr to recipient is linear and susceptible to degradation; thus to survive this DNA must undergo recombination with homologous sequences of the recipient chromosome.
		The integration of F into the chromosome to produce an Hfr is reversible, and the F plasmid may excise precisely from the chromosome to turn an Hfr cell back into a normal F+ cell.
	www.genetics.gla.ac.uk /level2/1b/lecture2.html (453 words)

	Problem Set 8 Answers
		Recombination is the transfer of bacterial genes from an Hfr or F’ strain to an F
		Hfr strains (F+ strains with an integrated F factor, such as B, C, and D) will have a much lower frequency of gene conversion.
		Hfr strains B and D are most likely to produce the F’ plasmid seen in F because of their proximity of lac to the fertility factor.
	www.columbia.edu /cu/biology/courses/c3032/answers-8.html (678 words)

	You are provided with cultures that have the following characteristics (Site not responding. Last check: 2007-10-21)
		Indicate the possible genotypes of a recombinant cell resulting from the conjugation of cultures 1 and 2.
		Culture 2 is the recipient cell and would be recombinant.
		If the donor cell (culture 1) becomes Hfr and then initiates conjugation, the recipient cell typically will receive a copy of part of the F factor and some of the main chromosome.
	campus.everettcc.edu /Departments/sciences/biology/rkratz/geneticsworksheet2p2.htm (329 words)

	Microbial Genetics: Gene Transfer
		In this process, the chromosome in the mother cell is replicated and a copy is allocated to each of the daughter cells.
		When living nonencapsulated cells were injected into a mouse, the mouse remained healthy and the colonies of nonencapsulated cells were isolated from the blood of the mouse.
		Replication of the Hfr chromosome begins at a fixed point within the F episome and the chromosome is transferred to the female as it replicates.
	plato.acadiau.ca /courses/biol/Microbiology/transfer.htm (1940 words)

	Microbiology: An Introduction Online Course Companion Chapter 8 -- Answers to End-of-Chapter Study Questions (Site not responding. Last check: 2007-10-21)
		During conjugation between an Hfr and an F cell, the chromosome of the Hfr cell, with its integrated F factor, replicates, and the new copy of the chromosome is transferred to the recipient cell.
		Mutations have a greater effect when a cell is growing because it is synthesizing DNA and enzymes.
		The cell does not regulate the rate at which DNA is synthesized, but it regulates the rate at which replication forks on the chromosomes are initiated.
	occawlonline.pearsoned.com /bookbind/pubbooks/tfc/chapter8/custom3/deluxe-content.html (925 words)

	Concepts of Genetics 6/e Chapter 7 -- Self-Grading Problems (Site not responding. Last check: 2007-10-21)
		Hfr bacterial cells exhibit the highest levels of gene transfer because
		In an Hfr mating with an F- cell, the recipient cell does not always become an Hfr or F+ cell because
		When a bacterial cell is transformed, after one round of cell division only one of the two resulting cells contains new genetic material because
	cw.prenhall.com /bookbind/pubbooks/klug3/chapter7/multiple1/deluxe-content.html (157 words)

	BIOL 211: MICROBIOLOGY
		DNA is transferred from a living donor cell to a living recipient cell through a sex pilus
		Hfr (high frequency of recombination) cells = F factor integrated into chromosome; may transfer copy of chromosomal genes during conjugation; may be interrupted and not transfer entire chromosome or even entire F factor (F- may be recombinant but remain F-)
		F’ cells = Hfr cell where F Factor leaves chromosome with chromosomal genes; can transfer chromosomal and F factor genes (F- cell may be recombinant and F+)
	www.centralia.ctc.edu /Depts/Science/Biol211/recombination.html (345 words)

	EPOB 3400 Microbiology Lecture 15
		Note that the F- cell is converted to an F+ cell as a result of a successful mating.
		Thus, during a mating of an Hfr cell and an F- cell, chromosomal DNA is transferred to the F- cell (but the F- usually does not become F+ or Hfr; why not?)
		The viral nucleic acids "reprogram" the host cell and causes it to replicate the virus that is then assembled and released from the host cell.
	spot.colorado.edu /%7Eschmidts/Teaching/EPOB3400/micro15-2000.html (1113 words)

	Microbiology: An Introduction Online Course Companion Chapter 8 -- Study Outline (Site not responding. Last check: 2007-10-21)
		DNA in cells exists as a double-stranded helix; the two strands are held together by hydrogen bonds between specific nitrogenous base pairs: AT and CG.
		Phenotype is the expression of the genes: the proteins of the cell and the properties they confer on the organism.
		F cells contain plasmids called F factors; these are transferred to the F2 cells during conjugation.
	occawlonline.pearsoned.com /bookbind/pubbooks/tfc/chapter8/custom1/deluxe-content.html (1606 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Helper T (TH) cellA specialized T cell* that often interacts with an antigen before B cells interact with the antigen.
		Hfr cellA bacterial cell* in which the F factor has become integrated into the chromosome; Hfr stands for high frequency of recombination.
		HybridomaA cell* made by fusing an antibody-producing B cell with a cancer cell.
	torre.fffcmpa.tche.br /Volumes/Microbiologia+Interativa/DATA/GLOSSARY/GLOSSCST/H.TXT (487 words)

	[No title]
		Hfr strain An E. coli cell in which an F plasmid is integrated into the chromosome, enabling transfer of part or all of the chromosome to an F- cell.
		interrupted-mating technique In an Hfr x F- cross, a technique by which donor and recipient cells are broken apart at specific times, allowing only a particular length of DNA to be transferred.
		time of entry In an Hfr F- bacterial mating, the earliest time that a particular gene in the Hfr parent is transferred to the F- recipient.
	www.rpi.edu /locker/53/001053/KEY7.DAT (743 words)

	F (Site not responding. Last check: 2007-10-21)
		A cell that carries a F-factor as an autonomous plasmid, which enables the cell acting as a donor (male) to transfer the F-factor to a recipient (female) cell.
		A cell which does not contain the F-factor, and hence able to act as a recipient (female) in a conjugative DNA transfer in matings with F
		Thin, proteinaceous filaments that extend from the cell surface of microbial cells and facilate adhesion to solid surfaces or other cells.
	www.sci.sdsu.edu /%7Esmaloy/Glossary/F.html (436 words)

	Figure 18-21 DNA Transfer by Bacterial Conjugation (Site not responding. Last check: 2007-10-21)
		(c) Conjugation between an Hfr donor cell and an F: cell involves the transfer of a copy of the Hfr genome through a mating bridge into the F: cell, beginning with the origin of transfer on the integrated F factor.
		Transfer is usually incomplete, because cells rarely remain in mating contact long enough for the entire bacterial chromosome to be transferred.
		Once inside the F: cell, parts of the Hfr DNA can undergo recombination with the DNA of the F: cell, just as in transformation or transduction (see Figure 18-19).
	www.mun.ca /biology/desmid/brian/BIOL2060/CellBiol18/CB18_21.html (213 words)

	Genetics
		The process is a lot simpler than mitosis or meiosis, because bacteria don't have multiple chromosomes that have to be sorted out correctly to the two daughter cells.
		Figure 8.11: A region along the F plasmid is homologous with several regions along the chromosome, and thus a recombination process (equivalent of a single cross-over) can cause F to become integrated into the chromosome.
		If allele A gets transferred over to the F-minus cell, followed by a double cross-over that spans gene alpha, the end result is that the F-minus cell's alpha genotype has changed from a to A.
	www.lehigh.edu /~jas0/G16.html (600 words)

	Amplification of Mutator Cells in a Population as a Result of Horizontal Transfer -- Funchain et al. 183 (12): 3737 -- ...
		Amplification of Mutator Cells in a Population as a Result of Horizontal Transfer -- Funchain et al.
		Hfr SA975 (29) donates markers in a clockwise fashion from a
		Cells acquire new traits not only by mutation, but also by horizontal transfer.
	jb.asm.org /cgi/content/full/183/12/3737 (2783 words)

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	SECTION VIII
		This small, circular DNA can replicate autonomously in the cell (so-called F+ cells), or can integrate into the host cell chromosome (cells containing this "episome" in their chromosome are called Hfr cells, as discussed below).
		In all three cases, it was found that cultures of cells are "competent" to undergo transformation only under special growth conditions, suggesting that preparing cells to take up DNA and undergo recombination is triggered by diffusable factors in the medium by mechanisms that are still not at all clear.
		If the Hfr strain has the ability to produce all these, describe how this tool of using conjugation to produce recombinants could be used to determine the relative locations of the genes for amino acid biosynthesis.
	www.waksmanfoundation.org /labs/wisteb/engineer.htm (7456 words)

	Hfr cell - Wikipedia, the free encyclopedia
		A hfr cell (also called hfr strain) is a bacterium with a conjugative plasmid (often F) integrated into its genomic DNA.
		Unlike a normal F+ cell, hfr strains will, upon conjugation with a F- cell, attempt to transfer their entire DNA through the pilus to the F- cell.
		This page was last modified 01:14, 4 June 2005.
	en.wikipedia.org /wiki/Hfr_cell (117 words)

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